THE SOLITARY EEE AND ITS ENEMIES. 363 



[n some specimens the white spots do not appear, so that the 

 insect is entirely black. Both sexes are coloured much in the 

 same manner, with the exception that the whole of the downy 

 clothing has a slight yellowish tinge. 



This is a parasitic insect, laying its eggs in the nest of one 

 of the burrowing bees, named Anthophora acervorum. This 

 Bee makes its nest in the holes of old walls, chalk-pits, and 

 similar localities, and is a very common insect, absolutely 

 swarming in some localities. It is subject to the attacks of 

 three other insects, which are the common Earwig, the Firetail- 

 fly, already described on page 330, and the Melecta, the two 

 Hymenopterous foes being often seen at once engaged in their 

 destructive work. The Melecta is, however, itself much 

 infested with the larvae of the Oil-beetle, which may be found 

 clinging to the under side of the thorax. 



At Fig. 4, Woodcut XXXVI. is sliown an example of one of 

 our most interesting gtoups of wild Bees, named scientifically 

 Osmia rufa. The specimen is a female. In this genus 

 the upper wings have one marginal and two submarginal 

 cells. The ocelli are set in a slight curve on the crown of the 

 head. 



The present species is black and hairy. The head of the 

 female is provided with a sort of horn on either side of the 

 face, the ends of the horns being slightly bent inwards. The 

 down on the middle or disc of the thorax is black, becoming- 

 dun towards the base, while on the sides and beneath it is ashen 

 grey. The male has no horns on the head, and the face is 

 covered with long white down. The antennae are lonsf and 

 slender, and the head and thorax, instead of being black, are 

 deep green-blue. The abdomen is covered with thick yellowish 

 down arranged in successive bands or belts. 



I mentioned just now that this insect belongs to one of our 

 most interesting groups of Bees. It has always interested me 

 greatly on account of the curious nests which it makes. 

 Generally, one species adheres strictly to one kind of locality, 

 but this is not the case with the Osmia, which adapts its 

 cells to various localities, according to the exigencies of the 

 moment. There are ten species of Osmia, each having some 

 particular point of interest attached to its mode of nesting. 



